1.  DNA Fingerprinting

2. Variation in Human DNA  Of 3 billion nucleotides in human DNA more than 99% are identical  Of 1% that are different  significant amount of code variations

3. RFLPs  For every 100 nucleotides inherited there is one site of variation, or polymorphism  These DNA polymorphisms change the length of strands cut by restriction enzymes  Fragments: restriction fragment length polymorphisms (RFLPs) RFLP ANIMATION  http://highered.mcgraw- hill.com/olcweb/cgi/pluginp op.cgi?it=swf::535::535::/sit es/dl/free/0072437316/120 078/bio20.swf::Restriction Fragment Length Polymorphisms http://highered.mcgraw- hill.com/olcweb/cgi/pluginp op.cgi?it=swf::535::535::/sit es/dl/free/0072437316/120 078/bio20.swf::Restriction Fragment Length Polymorphisms

4. Short Tandem Repeats  Most DNA in a chromosome is not used to code for genes  More likely to find differences in these regions which do not seem to be essential to an organism’s development  Regions contain sequences that repeat many times  (e.g. GTCAGTCAGTCAGTCA)

5. What can STRs Tell Us?

6. Link Between RFLPs and DNA Fingerprinting  Difference in fragments leads to a DNA Fingerprint  Scientists have identified more than 3000 RFLPs in the human genome  Distinct RFLP patterns can be used: to trace family relationships, to track genetic disorders, in forensics, understand more about endangered species

7. Accuracy of DNA Fingerprinting  Accurate to within 1 in 1 billion

8. Gel Electrophoresis Review: Agarose Gel  Agarose: extracted from seaweed  Heated  Melts  Solidifies and forms a matrix of microscopic pores

9. Agarose Concentration  Size of pores depends on the agarose concentration  The lower the agarose concentration, the larger the pore size  Usually use from 0.5% to 2%

10. Gel Separation  Charge: buffer, power supply, DNA  Size: cut into pieces by restriction enzymes, small pieces move easier through the pores

11. Loading the DNA Loading Dye  used to help visualize when loading the gel  Used for tracking the progress of the gel  Does NOT bind to the DNA

12. Visualizing DNA Visible Light Stain (Usually Blue) UV Light Stain (Ethidum Bromide)